A semiconductor laser that is a type of a solid-state light source is suitable for a light source for a projector because light emitted from a semiconductor laser has a high tendency to travel in straight lines and it has high color saturation in a high brightness condition. When a semiconductor laser is used as a light source for a projector, the temperature of the semiconductor laser rises, and thus it is necessary for the semiconductor laser to be maintained at a predetermined temperature to output light of a desired wavelength in a stable state. Accordingly, a semiconductor laser is cooled by circulating liquid coolant in a cooling jacket to be used as a cooling member for cooling the semiconductor laser, which is provided on the rear side of a semiconductor laser.
As an example, Patent Literature 1 discloses a configuration in which three light sources provided in a projection-type image display device are cooled by two cooling systems. The light sources are provided in different heat conduction units, and the heat generated by each light source is thermally conducted to coolant that flows through a coolant flow channel via the heat conduction unit.